Three-Axis Nested Fiber Optic Gyroscope

Jerold P. Gilmore, Lawrence Freier, Ernest Nolan, Michael Perlmutter and Mark Bowser, John Maglieri

Abstract:	This paper provides a description of the Three-Axis Nested Fiber Optic Gyroscope (FOG). The Three-Axis FOG is being developed by System Engineering Solutions, Inc. (SES) and its prime subcontractor Fibersense Technology Corp. (FTC) under sponsorship by the Aviation Applied Technology Directorate of the US Army Aviation and Missile Command, a Phase II SBIR. The Three-Axis FOG being developed by SES is based on the design of a nested configuration of three free standing elliptical fiber optic coils, patent pending, in a supporting assembly that yields substantial size and weight advantages. It permits use of an integrated three axis environmental shield and thermal isolation enclosure. The core nest ed assembl y of three fr ee st andi ng coi l s mounted in its supporting structure with electro-optical components weighs less than 0.4 pounds and its volume is 19 cubic inches, not including shielding and isolation enclosure featur es whi ch are appl i cati on and i nt er face dependent. The corresponding Performance Projections for the Army Three-Axis Gyroscope with a 500 deg/sec rate range are, uncompensated, Bias of 0.007 deg/hr, 1 sigma, Angle Random Walk of 0.002 deg/rt-hr. To date SES has completed the detailed design of the nested configuration and the enclosure. The supporting FTC digital control and interface electroni cs has been adapt ed to the SES opt i cal packagi ng confi gu rati on. Fabrication of two deliverable Nested Fiber Optic Gyro Systems was initiated May 1999. Ext ensi ve t est i ng of t he FTC electroni cs wi t h the Phase I SBIR FOG has been conducted to verify compatibility bet ween the FOG electro -opt i cal featu res and t he di gi t al cont rol electroni cs. Speci fi c emphasi s was on t he determination of thermal and voltage sensitivities. To date in temperature tests, across 20 degC temperature cycling, bias performance of 0.033 deg/hr has been achieved with no temperature control or compensation modeling. Angle Random Walk of 0.0038 deg/rt-hr has also been demonst rated. The Phase II coi l has 23% more coil length and unique thermal isolation and control is implemented. This enhanced design is expected to yield the performance projections tabulated above.
Published in:	Proceedings of the 55th Annual Meeting of The Institute of Navigation (1999) June 27 - 30, 1999 Royal Sonesta Hotel Cambridge, MA
Pages:	697 - 704
Cite this article:	Gilmore, Jerold P., Freier, Lawrence, Nolan, Ernest, Perlmutter, Michael, Bowser, Mark, Maglieri, John, "Three-Axis Nested Fiber Optic Gyroscope," Proceedings of the 55th Annual Meeting of The Institute of Navigation (1999), Cambridge, MA, June 1999, pp. 697-704.
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